Patent foramen ovale (PFO) closure method and device

ABSTRACT

The present invention provides methods and devices for closing two overlapping layers of tissue in a mammalian heart, for example a patent foramen ovale (PFO). The closure devices may take a number of different forms and may be retrievable. In some embodiments, a device is sized and shaped to extend from septum secundum, into the left atrium, through septum primum, and into the right atrium, such that the first and second ends cooperate to provide a compressive force to the overlapping layers of tissue. In some embodiments, the closure devices may be delivered with a catheter capable of puncturing mammalian tissue.

CROSS-REFERENCE TO RELATED APPLICATIONS

This Application is a Divisional of U.S. patent application Ser. No.10/341,802, entitled Patent Foramen Ovale (PFO) Closure Method andDevice, filed Jan. 14, 2003, and incorporated herein by this reference.

FIELD OF THE INVENTION

The invention relates to occlusion devices and methods for the closureof physical anomalies, like septal apertures, such as patent foramenovale and other septal and vascular defects.

BACKGROUND OF THE INVENTION

A patent foramen ovale (PFO) as shown in FIG. 1, is a persistent,one-way, usually flap-like opening in the wall between the right atrium10 and left atrium 12 of the heart. Since left atrial (LA) pressure isnormally higher than right atrial (RA) pressure, the flap typicallystays closed. Under certain conditions, however, RA pressure can exceedLA pressure creating the possibility for right to left shunting that canallow blood clots to enter the systemic circulation. In utero, theforamen ovale serves as a physiologic conduit for right-to-leftshunting. After birth, with the establishment of pulmonary circulation,the increased left atrial blood flow and pressure results in functionalclosure of the foramen ovale. This functional closure is subsequentlyfollowed by anatomical closure of the two over-lapping layers of tissue:septum primum 14 and septum secundum 16. However, a PFO has been shownto persist in a number of adults.

The cause of ischemic stroke remains cryptogenic (of unknown origin) inapproximately 40% of cases. Especially in young patients, paradoxicalembolism via a PFO is considered in the diagnosis. While there iscurrently no proof for a cause-effect relationship, many studies haveconfirmed a strong association between the presence of a PFO and therisk for paradoxical embolism or stroke. In addition, there is goodevidence that patients with PFO and paradoxical embolism are atincreased risk for future, recurrent cerebrovascular events.

The presence of a PFO has no therapeutic consequence in otherwisehealthy adults. In contrast, patients suffering a stroke or transientischemic attack (TIA) in the presence of a PFO and without another causeof ischemic stroke are considered for prophylactic medical therapy toreduce the risk of a recurrent embolic event. These patients arecommonly treated with oral anticoagulants, which have the potential foradverse side effects, such as hemorrhaging, hematoma, and interactionswith a variety of other drugs.

In certain cases, such as when anticoagulation is contraindicated,surgery may be used to close the PFO. To suture a PFO closed requiresattachment of septum secundum to septum primum with either aninterrupted or a continuous stitch, which is the common way a surgeonshuts the PFO under direct visualization.

Nonsurgical closure of PFOs has become possible with the advent ofumbrella devices and a variety of other similar mechanical closuredesigns, developed initially for percutaneous closure of atrial septaldefects (ASD). These devices allow patients to avoid the potential sideeffects often associated with anticoagulation therapies.

Currently available designs of septal closure devices, however, presentsuch drawbacks as technical complexity of implantation procedure, highcomplication rates (thrombus, fractures, conduction system disturbances,perforations, residual leaks), high septal profile, large masses offoreign material, and lack of anatomic conformability especially to thePFO flap-like anatomy, as most were originally designed to close ASD's,which are true holes. Additionally, some septal closure devices arecomplex to manufacture, which can result in lack of consistency inproduct performance.

SUMMARY OF THE INVENTION

In one aspect, the present invention provides a method of closing twooverlapping layers of tissue in a mammalian heart, e.g., a patentforamen ovale (PFO), using a closure device that applies a compressiveforce to at least one of the layers of tissue. The closure device may beretrievable, such that it may be removed after a period of timesufficient to allow the overlapping layers of tissue to fuse together.If necessary to sufficiently close the length of the layers of tissue,multiple closure devices may be administered. The closure devices may bedelivered with a catheter capable of puncturing mammalian tissue in atleast one location.

The closure device of the present invention may take a number ofdifferent forms. For example, the closure device may have first andsecond ends, both of which may be capable of puncturing mammaliantissue. The device may be a structure such as a ring with a gap, afolded ring, at least one grappling hook member joined to at least onecurved arm by a joinder member, opposed grappling hook members joined bya central connecting member, a grappling hook member and a centralconnecting member, or a closure device anchor joined to a structure ofsufficient diameter to hold the device in place against the overlappinglayers of tissue. In some embodiments of the present invention, theclosure device is sized and shaped such that it extends from septumsecundum in the left atrium, into the left atrium, through septumprimum, into the right atrium, and to septum secundum in the rightatrium. Some retrievable devices include elongate tethers to facilitatetheir removal. Each of these devices has certain advantages, and oneskilled in the art will be capable of selecting the device appropriatefor a given application.

The ends of the closure device may also take a number of differentforms. For example, at least one end may form a disc or a closure deviceanchor, such as a coil, hook, or corkscrew. These end structures help tomaintain the device in place. One of the ends, for example the secondend, may take the form of a knot or a structure similarly capable ofholding the device in place and applying a sufficient compressive forceto the overlapping layers of tissue. In some embodiments, the endstructure may be adjusted to alter the compressive force applied to theoverlapping layers of tissue. As previously mentioned, either or both ofthe first and second ends may be capable of puncturing mammalian tissue.In some embodiments, the first end of the device is a septal punctureneedle.

The closure device may be formed of any of several materials, such asflexible polymer materials, bioabsorbable materials, shape memorymaterials, metals, noble metals, or swellable foams. In particularembodiments, the device includes nitinol. Some of the devices are formedfrom a single piece of material, while others are formed from multiplepieces of material joined together.

Some closure devices according to the present invention are intended topuncture septum primum upon insertion into the heart. For example, sucha device may be inserted into the right atrium of the heart and punctureseptum primum to enter the left atrium of the heart. At this point, thefirst end of the device may simply be deployed into the left atrium, orthe first end of the device may be deployed into the left atrium and atleast partially puncture septum secundum. In those embodiments where thefirst end of the device at least partially punctures septum secundum,the first end may be embedded in septum secundum or may completelypuncture septum secundum such that the first end extends into the rightatrium. The second end of the device may then be positioned againstseptum secundum in the right atrium, thereby providing a compressiveforce to the septal tissues. In other embodiments, the second end isalso positioned in the left atrium while another portion of the device,such as a fold, is positioned in the right atrium, thereby compressingthe septal tissues between the device.

Alternatively, some closure devices according to the present inventionare intended to be inserted between the overlapping layers of tissue,e.g. through the PFO tunnel, to enter the left atrium. In theseembodiments, the first end of the device is then deployed in the leftatrium and the second end of the device is deployed in the right atrium,thereby providing a compressive force to the septal tissue. As discussedabove, at least one of the ends of the device may partially punctureseptum secundum.

These and other features will become readily apparent from the followingdetailed description wherein embodiments of the invention are shown anddescribed by way of illustration.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagrammatic sectional view of a Patent Foramen Ovale (PFO);

FIG. 2 is a view in side elevation of the PFO closure device withmechanical anchors of the present invention;

FIGS. 3 a, 3 b and 3 c illustrate the steps in the deployment of the PFOclosure device of FIG. 2;

FIG. 4 is a view in side elevation of a second embodiment of the PFOclosure device with mechanical anchors of the present invention;

FIGS. 5 a, 5 b and 5 c illustrate the steps in the deployment of the PFOclosure device of FIG. 4;

FIG. 6 is a view in side elevation of a catheter and septal punctureneedle used to pierce septum primum;

FIG. 7 is a view in side elevation of a needle anchor for PFO closure;

FIG. 8 is a view in side elevation of a suture and anchor used for PFOclosure;

FIG. 9 is a diagram of multiple anchor placement for PFO closure;

FIGS. 10 a, 10 b and 10 c illustrate the steps in the deployment of arivet and suture type of PFO closure device;

FIGS. 11 a, 11 b, 11 c and lid illustrate the steps in the deployment ofa removable PFO closure device;

FIGS. 12 a, 12 b and 12 c illustrate the steps in the deployment of amultiple hook PFO closure device;

FIG. 13 is a view in side elevation of an alternative structure of thesecond embodiment of the PFO closure device with mechanical anchors ofthe present invention;

FIG. 14 is a view in side elevation of an alternative structure of thesecond embodiment of the PFO closure device with mechanical anchors ofthe present invention; and

FIGS. 15 a, 15 b, and 15 c are an end face view from the right atrium,an end face view from the left atrium, and a side elevation view,respectively, of the deployed alternative structure of the secondembodiment of the PFO closure device with mechanical anchors of thepresent invention.

DETAILED DESCRIPTION

Referring to FIGS. 2 and 3, a PFO closure device with mechanical anchorsindicated generally at 18 includes opposed grappling hook members 20 and22 connected by a central connecting member 24. When the PFO closuredevice 18 is deployed, the grappling hook members 20 and 22 each includetwo or more curved hooks. In FIGS. 2 and 3, three curved hooks 26, 28and 30 form the grappling hook member 20 and three curved hooks 32, 34and 36 form the grappling hook member 22. As shown in FIG. 2, thegrappling hooks 26, 28, 30, 32, 34, and 36 extend radially from thecentral connecting member 24. The grappling hooks of grappling hookmembers 20 and 22 have the same geometry but are rotated such that eachgrappling hook of grappling hook member 20 is situated precisely betweentwo opposed grappling hooks of grappling hook member 22. The anglebetween any two grappling hooks of grappling hook members 20 and 22 maybe determined by the formula 360°/(number of hooks per grappling hookmember). To fit within a catheter, these hooks may all be straightenedoutwardly and compressed to lie along the longitudinal axis of thecentral connecting member 24. In this form, the PFO closure deviceextends longitudinally within a catheter 38.

To deploy the PFO closure device 18, the catheter 38 is inserted fromthe right atrium 10 through the PFO tunnel, i.e. between septum primum14 and septum secundum 16, into the left atrium 12. As shown in FIG. 3a, the grappling hook member 20 is deployed into the left atrium. Next,as shown in FIG. 3b, the catheter 38 is drawn back into the right atriumand the grappling hooks 26, 28 and 30 are drawn back and embedded in theleft sides of septum primum and septum secundum. The central connectingmember 24 extends at an angle through the PFO tunnel permitting septumprimum and septum secundum to be drawn to the closed position andsecured by the grappling hooks 26, 28 and 30. Finally, as shown in FIG.3 c, the catheter 38 is drawn back to permit the grappling hook member22 to deploy, and grappling hooks 32, 34 and 36 pierce the right side ofseptum primum and septum secundum.

The grappling hook members 20 and 22 may be formed of flexible,spring-like, bioabsorbable polymer material so as to permit movementfrom the compressed straight shape to the curved hook shapes followingdeployment from the catheter 38. The central connecting member 24 mayalso be formed of bioabsorbable material, such as an absorbable suturematerial, so the device will ultimately leave no foreign substance ineither atrium. Alternatively, the grappling hook members 20 and 22 maybe formed of spring metal or of a shape memory material, such asnitinol. When the PFO closure device is not formed of bioabsorbablematerial, it is possible to form the device with only the grappling hookmember 20 and a central connecting member 24 so that the device isrepositionable and retrievable. When the device is made of abioabsorbable material or is not intended to be retrievable, the ends ofgrappling hooks 26, 28, 30, 32, 34 and 36 may further include a barb tomaintain the device in the septal tissue. In some embodiments, thegrappling hook members 20 and 22 serve as tissue scaffolds, and arecovered with a vascular material, such as polyester, biological tissue,bioresorbable polymer, or spongy polymeric material.

As shown in FIG. 3, the closure device will conform, at least to someextent, to the septal tissue that it compresses. The extent of thisconformance depends upon the material from which the device was formed:a device formed of a spring metal or shape memory material will conformto the surrounding septal tissue to a lesser extent than one formed of aflexible, bioabsorbable polymer material.

FIG. 4 shows a second embodiment of a PFO closure device with mechanicalanchors indicated generally at 40. This device, when deployed, forms aring hook design that terminates in two opposed, pointed ends 42 and 44.The device may be straightened to pass through a catheter 38. To deploythe device as shown in FIGS. 5 a, 5 b and 5 c, the catheter is caused topierce septum primum 14 and enter the left atrium where the pointed end42 is deployed. Then, as shown in FIG. 5 b, the catheter is drawn backthrough septum primum to draw the device through septum primum and embedthe pointed end 42 in the left side of septum secundum. Finally, asshown in FIG. 5 c, the catheter is withdrawn to fully deploy the PFOclosure device and the pointed end 44 is embedded in the right side ofseptum secundum to compress septum primum and septum secundum together.As shown in FIGS. 4 and 5, the ring PFO closure device 40, whendeployed, may include a gap that is slightly smaller than the thicknessof septum secundum into which it is embedded. In some embodiments, theopposed ends 42 and 44 of the deployed PFO closure device 40 contacteach other or overlap.

As shown in FIGS. 13 and 14, closure device 40 may take alternativeforms. For example, closure devices 90 and 100 are formed as partialrings terminating in two pointed ends 92 and 94 or 102 and 104 andhaving at least one fold therebetween. Closure devices 90 and 100 aredeployed in a manner similar to that described above and shown in FIG.5. When deployed, the pointed ends 92 and 94 or 102 and 104 puncture thesurface of septum secundum exposed in the left atrium and at least oneof the folds contacts the surface of septum secundum exposed in theright atrium (FIGS. 15 a and 15 b). Septum primum and septum secundumare thus compressed between the pointed ends and at least one of thefolds of the device (FIG. 15 c).

Multiple PFO closure devices 40, 90 or 100 can be inserted until thephysician is satisfied with the resultant PFO closure. Again, the PFOclosure devices may be formed of flexible, bioabsorbable polymermaterial, spring metal, other spring-like non-bioabsorbable material, orshape memory material. The choice of material will affect the degree towhich the device conforms to the surrounding septal tissue. As shown inFIGS. 4, 13, and 14, the PFO closure device may be a monolithicstructure.

A PFO may also be closed with one or more sutures. As used in the artand indicated in the Figures, “suture” refers to a single connectionused to hold two pieces of material or tissue together and need not be acontinuous stitch. However, to suture a PFO closed has conventionallyrequired the attachment of septum secundum to septum primum with acontinuous stitch. This need for a continuous stitch can be eliminatedby implanting sutures across the PFO using implantable suture anchors.As shown in FIGS. 6 and 7, a catheter 46 is used to puncture septumprimum and then septum secundum. In the case of septum primum, thepuncture creates a hole through which the catheter can pass; in the caseof septum secundum, the puncture may be a depression that does not passthrough septum secundum. A single puncture may be made in septumsecundum as shown in FIGS. 6-8, or, as subsequently described and shownin FIG. 9, multiple punctures may be made. These punctures are madeusing a sharp pointed needle tip 48. Following puncture to a desireddepth, the catheter 46 surrounding the needle 48 is withdrawn and theneedle component returns (most likely via shape memory) to itspredetermined anchor-shape.

The anchors are most likely fabricated from a shape memory alloy, suchas nitinol, although they could be made from a flexible, bioabsorbablepolymer or a noble metal, each having their own advantage—no long termimplant issues with bioabsorbable anchors and excellent radiopacity withanchors fabricated from a noble metal, such as platinum-iridium. Theremainder of the suture may be formed of any suitable material,including wire, polymeric materials, and bioabsorbable materials.

The suturing method includes using a standard septal puncture techniqueto locate and puncture septum primum. Following this, several approachesexist. One would be that the septal puncture needle would be withdrawnfrom the catheter and the suturing system then delivered through thecatheter (the septal needle catheter would maintain position acrossseptum primum during the exchange). Alternatively, a wire could beplaced through the septal needle catheter to maintain position and thesuture system could be delivered over the wire, or the septal punctureneedle could become part of the suture system. Following delivery of thesuture system, the proximal end of the suture may then be tied off so asto secure the system in place and keep the PFO closed. As describedbelow for the rivet design suture system and shown in FIG. 10 c, theproximal end of the suture may be formed into a knot, i.e. the end ofthe suture may be formed into a structure having a diameter larger thanthat of the catheter used to puncture septum primum so as to ensure thatthe suture system remains in place. Other suitable structures for theproximal end of the suture include, but are not limited to, coils,spirals, and other adjustable mechanisms. This structure should applysufficient compression to hold septum primum and septum secundumtogether. The structure may be adjustable, such that the level ofcompression may be altered as necessary. Multiple sutures may beinserted until the physician is satisfied with the PFO closure.

In FIG. 8, a suture 50 is delivered through the septal needle catheterfollowing the removal of the needle. A suture catheter 52 enters theleft atrium through the septal needle catheter, is pulled back againstseptum secundum, setting the needle tip(s) 54 deep within it or throughit, if it is thin enough. The tip could be either radiopaque, echogenic,or both, to be visible by x-ray (fluoroscopy) and/or cardiac echo. Onceproper position is determined, the constricting system (a hypotube or aseries of con-axial hypotubes in the embodiment where multiple needlesare simultaneously delivered) is withdrawn, allowing the suture anchor56 to form into a pre-determined shape tissue anchor, most likely viashape memory properties. The anchor 56 on the end of the suture 50 hasbeen embedded in septum secundum and expands to anchor the suture, whichpasses through septum primum once the suture catheter is removed. Theanchor shape can be one of many different options, including but notlimited to a coil, hook, corkscrew, or grappling hook.

In those cases where a true puncture through septum secundum can bemade, an anchor can be placed entirely in the right atrium, leavingnothing but suture in the left atrium. These anchors may be short stripsor cylindrical rods made from a metallic or polymeric material that isbiostable or bioabsorbable, or a piece of swellable foam, such asIvalon.

In another embodiment, the septal needle catheter crosses septumsecundum in multiple locations simultaneously. In this embodiment, thefinal result, as seen from the left atrium in an end face view of septumprimum and septum secundum, would be as shown in FIG. 9, where aplurality of spaced anchors 58 engage septum secundum.

A rivet design suture system 60 is shown in FIGS. 10 a, 10 b and 10 c.Here a suture 62 and anchor 64 are contained within a catheter 66, whichpierces both septum secundum and septum primum. The anchor 64, which isformed of a firm material, such as a metal disc, a small hook (such asthe shape memory hooks previously described), or a piece ofbio-absorbable polymer, is then deployed into the left atrium, and thesuture 62 and catheter 66 are then pulled back as shown in FIG. 10 b tocompress the two septa together. The suture 62 can then be knotted withknot 68, as shown in FIG. 10 c, to secure the system 60 in place to keepthe PFO closed, i.e. the end of the suture may be formed into astructure having a diameter larger than that of the catheter used topuncture septum primum so as to ensure that the suture system remains inplace. Other suitable structures for the second end of the sutureinclude, but are not limited to, coils, spirals, other adjustablemechanisms. As shown in FIG. 10 c, this structure should applysufficient compression to hold septum primum and septum secundumtogether. The structure may be adjustable, such that the level ofcompression may be altered as necessary. Multiple rivet systems can beinserted until a physician is satisfied with the PFO closure.

The PFO closure device of the present invention may be formed in amanner to facilitate removal once septum primum and septum secundum arefused. An exemplary removable PFO closure device 70 is deployed in themanner illustrated by FIGS. 11 a-11 d. The PFO closure device 70 may bedelivered by a delivery catheter or sheath 72 and includes a grapplinghook member 74 joined to a curved arm 76 by an enlarged tip joindermember 78. At least one of the grappling hook member and curved arm ofthe PFO closure device may be curved relative to the other. An elongatetether 80 is connected to the tip joinder member 78 and extends backthrough the catheter 72. The tether 80 can be coated to minimize traumato the veins.

To deploy the removable PFO closure device 70 according to oneembodiment of the invention, the grappling hook member 74 is passedthrough septum primum 14 (FIG. 11 b), and the grappling hook, when freeof the catheter, curves in a manner convex relative to the surface ofseptum secundum and penetrates septum secundum 16 (FIG. 11 c). Then, thegrappling hook is drawn back toward the catheter by the tether 80 toapply tension to the tissue causing septum secundum to be drawn intocontact with septum primum. Then the curved arm 76 is deployed (FIG. 11d) and curves in a manner concave relative to septum secundum so as toengage septum secundum as the catheter is drawn back. The compressiveforce applied by the grappling hook and the curved arm hold septumprimum and septum secundum tightly together. The grappling hook 74 andcurved arm 76 are preferably formed of shape memory material, such asnitinol, so that they respond to body temperature when deployed from thecatheter 72 to form the shape shown in FIG. 11 d.

Once the PFO closure device 70 is in place, the catheter 72 is withdrawnand the free end of the tether 80 is attached to a button subcutaneouslyand allowed to remain in place for a period of time sufficient to allowthe two septa to fuse together. Then the device is pulled through septumprimum and into a recovery sheath by means of the tether 80 and removed.

The PFO closure device 70 can be deployed as shown in FIG. 11 withoutthe tether 80 to provide a free standing device with the grappling hook74 and arm 76 being formed to press the two septa 14 and 16 together.The device may later be removed by a removal device, which grabs thejoinder member 78 and draws the device through septum primum 14 and intoa removal sheath.

Instead of a single opposed grappling hook 74 and curved arm 76, the PFOclosure device can include a plurality of opposed grappling hooks andcurved arms radially extending in a spaced relationship from the joindermember 78. Such a device 82 is shown in FIG. 12. Here, the PFO closuredevice includes a plurality of grappling hooks 84 and a plurality ofopposed curved arms 86 which are enclosed in a delivery catheter 72. Asmall hole 88 is created in septum primum 14 to permit insertion of thecatheter into the left atrium and the grappling hooks 84 are deployed asshown in FIG. 12 a. Then, the delivery catheter is drawn back to engagethe hooks with both septum secundum and septum primum as shown in FIG.12 b. Next, as shown in FIG. 12 c, the catheter is drawn away to releasethe curved arms 86, which engage the two septa in opposed relationshipto the grappling hooks 84. The device may have many, e.g. eight, opposedgrappling hooks and curved arms. As in the case of the PFO closuredevice 70, the device 82 may be removed by grasping the tip joindermember 78.

The device 82 may be permanently deployed by inserting the catheterthrough the PFO channel between septum secundum and septum primum intothe left atrium to deploy the grappling hooks 84. Then, the catheter iswithdrawn back through the PFO channel to release the curved arms 86.

Having described embodiments of the present invention, it should beapparent that the invention is capable of other and differentembodiments and may be modified in various respects, all withoutdeparting from the scope of the invention as defined by the appendedclaims. Accordingly, the foregoing drawings and description are to beregarded as illustrative in nature and not in a restrictive or limitingsense.

1. A device for closing two overlapping layers of septum primum andseptum secundum dividing a left atrium and a right atrium in a mammalianheart, said device having first and second ends, wherein said device issized and shaped to extend from septum secundum, into the left atrium,through septum primum, and into the right atrium, said first and secondends cooperating to provide a compressive force to the overlappinglayers of tissue.
 2. The device of claim 1, wherein said first end isembedded in, and does not extend through, septum secundum.
 3. The deviceof claim 2, wherein said first end is formed into a coil, hook,corkscrew, or other anchor.
 4. The device of claim 1, wherein said firstend includes a material selected from the group consisting ofbioresorbable materials, noble metals, shape memory materials, metals,polymeric materials, and swellable foams.
 5. The device of claim 4,wherein said shape memory material includes nitinol.
 6. The device ofclaim 1, wherein said first end includes a septal puncture needlecapable of puncturing mammalian tissue.
 7. The device of claim 1,further comprising a catheter containing said device in an elongated,low-profile form, said first end being expandable to form an anchor andsaid second end being adjustable to alter a compressive force applied tothe overlapping layers of tissue.
 8. The device of claim 1, wherein saiddevice is sized and shaped to further extend to septum secundum in theright atrium.
 9. The device of claim 8, wherein said device includes aring with a gap terminating in first and second opposed, pointed endsfor puncturing mammalian tissue.
 10. The device of claim 9, wherein saiddevice includes a material selected from the group consisting offlexible polymers, bioabsorbable materials, spring metals, and shapememory materials.
 11. The device of claim 10, wherein said deviceincludes nitinol.
 12. The device of claim 9, wherein said deviceconsists essentially of a monolithic partial ring.
 13. The device ofclaim 9, wherein said device includes a gap slightly smaller than thethickness of the overlapping layers of tissue to which it is connected.14. The device of claim 9, wherein said device includes a gap slightlysmaller than the thickness of septum secundum.
 15. The device of claim9, wherein said first and second ends overlap each other.
 16. The deviceof claim 1, wherein said device includes a partial ring with first andsecond ends and at least one fold therebetween.
 17. The device of claim16, wherein said at least one fold cooperates with said first and secondends to apply a compressive force to said overlapping layers of tissue.18. The device of claim 16, wherein said device consists essentially ofa monolithic partial ring.
 19. The device of claim 1, wherein saiddevice is sized and shaped to further contact the surfaces of septumprimum exposed in both the left and right atria.